Types of reaction to pilocarpine in patients with low-tension glaucoma

PURPOSE. To determine the types of reaction to pilocarpine in patients with low-tension glaucoma (LTG) and study the nature of fluid outflow along the main pathways in different types of reaction to pilocarpine.METHODS. The observation group included 21 people (42 eyes) with LTG aged 51 to 80 years (average age 68±9.8 years). The criteria for inclusion in the study were emmetropic refraction and no previous laser and surgical interventions on the examined eye. The anterior chamber angle corresponded to medium–wide or wide according to the classification by A.P. Nesterov. The initial stage of LTG was established in 16 eyes, developed stage — 12 eyes, advanced stage — 14 eyes.The examination was carried out both in patients with newly diagnosed glaucoma and in patients with previously established diagnosis who received hypotensive drug therapy; in the latter case the patients were recommended to cease instillations of hypotensive drugs 10–14 days prior to the examination.RESULTS. Among the studied LTG patients, positive pilocarpine test was registered in 5 eyes (12%), negative — in 6 eyes (14%), and paradoxical — in 31 eyes (74%).The obtained data revealed no statistically significant differences in the initial values of anterior chamber depth, lens thickness and axial eye length between patients with paradoxical and positive reactions to pilocarpine. Therefore, there are no anatomical prerequisites for the development of a particular type of reaction to the pilocarpine test in the studied eyes.The ease of outflow coefficient (EOC) for the drainage pathway is significantly reduced in patients with positive reaction to pilocarpine, which in absolute numbers approaches normal values. In these patients the drainage outflow reserves are preserved.In persons with paradoxical reaction to pilocarpine, EOC for the drainage pathway is significantly reduced and is low in absolute numbers. Deterioration of the outflow along the uveoscleral pathway in pilocarpine instillations leads to elevated intraocular pressure.CONCLUSION. The majority of patients with low-tension glaucoma have a paradoxical reaction to the pilocarpine test. The sufficiently high sensitivity of the sample allows recommending it as a diagnostic test for this type of glaucoma.Different types of reaction to pilocarpine in patients with low-tension glaucoma are associated with the intensity of intraocular fluid outflow over the drainage and uveoscleral pathways.